


Flatworm Wincestiel

by omgbubblesomg



Category: Supernatural
Genre: Crack, M/M, Mpreg, Multi, Other, barbed penises, biological accuracy is sexy, flatworm sex, yes you heard me
Language: English
Status: Completed
Published: 2018-04-19
Updated: 2018-04-19
Packaged: 2019-04-24 23:47:13
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,771
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14366337
Author URL: https://archiveofourown.org/users/omgbubblesomg/pseuds/omgbubblesomg
Summary: Sam is no ordinary flatworm. Sam is ahornyflatworm. And even though his species usually fills the bottom rung of the food ladder, today he is feeling ratherpredatory.





	Flatworm Wincestiel

**Author's Note:**

  * For [GertieCraign](https://archiveofourown.org/users/GertieCraign/gifts), [blondess](https://archiveofourown.org/users/blondess/gifts), [sweet_sally](https://archiveofourown.org/gifts?recipient=sweet_sally).



> Decided AO3 needed this nonsense too. Bonus 4th chapter for everyone playing at home. You can witness the original [here](https://omgbubblesomg.tumblr.com/post/172742762796/flatworm-wincest-this-is-gertiecraigns-fault)  
> Blame this monstrosity on gertie, blondess and sweet_sally
> 
> Artwork by @[ryugarika-blog](http://ryugarika-blog.tumblr.com/post/172834087277/flatworm-wincestiel) because apparently i had to drag other people into this hell-hole with me.
> 
> (for scientific transparency i should inform you that flatworm dicks are technically called stylets but if that's the biggest transgression i make in this fic then idk I guess i did alright.)

Sam worms his way around a pebble, and then worms his way down a slope. ‘Worming’ is really the best way to describe Sam’s movements, since Sam is, in fact, a worm. A flatworm, to be precise. As such, most everything he does is done in a worm-y sort of fashion.

Right now, Sam is worm-ily wriggling through a little crevice in his underwater lair. Most flatworms don’t have lairs but, as we are about to find out, Sam is no ordinary flatworm. Sam is a _horny_ flatworm. And even though his species usually fills the bottom rung of the food ladder, today he is feeling rather _predatory._

He worms his way around a coral and there, less than a foot away (a human foot, not a flatworm foot), is Dean.

If flatworms were able to talk, their conversation would go something like this:

“Hey! Dean!”

“Sammy! What’s up bro?”

“It’s _Sam._ ” (Most flatworms don’t have a considerable preference for any specific name, but Sam is very particular about his).

“Sure thing, bitch.”

“Shut up, jerk.”

“Wait, uh… why do you have your cock out?”

“Because I want to stab you in the abdomen and jizz into your insides, duh.”

“Dude. Kinky. Also no. I wanna stick _my_ jizz in _your_ abdomen!”

Unfortunately, given the lack of a tongue, voicebox, or lungs, the conversation is carried out not in words, but in bodily undulations and dick-waving. Sam’s penis is double-headed and pointed and he waves it menacingly at Dean. He takes great pride in having a particularly large, sharp penis, but when he looks at Dean he can see that he also appears to have a large penis, and the two barbs look equally as sharp as Sam’s.

He doesn’t have a throat, but he definitely gulps.

Too late for second guessing.

 

* * *

 

Sam has beaten many worthy adversaries before, but Dean is his equal in almost every way, and their dick fencing is prolonged and tiresome. Sam worries that even if he does win, he won’t have enough energy to beat anyone else and he’ll be impregnated before the end of the mating season. Ugh!

Dean lunges at him and Sam sideworms, which is like sidestepping if you don’t have feet. Which Sam doesn’t.

Sam takes up an offensive stance, which doesn’t look very much different to a defensive stance, but it’s important to have the mindset of a fighter if you plan on stabbing people with your dick, so offensive stance it is.

He stabs three times in quick succession, and Dean parries each one, their dicks glancing off each other. He tries for a sideways thrust and their pointed barbs lock as they each try to gain the advantage.

“Why don’t you want my jizz?” he yells. Well, he would yell. If he had a voice. He kind of wriggles his upper body a bit and hopes that gets his point across instead.

“Why don’t you want  _my_  jizz?” Dean body-wiggles back.

They break apart and circle each other, like an underwater cowboy movie standoff. Sam has never seen a cowboy movie but he would probably enjoy it if he did.

Dean makes a complicated wave with his dick. Something along the lines of a “Why don’t we stab each other at the same time?” kind of dick wave.

Sam curls his dick up, which might be like a laugh if he knew what a laugh was. “Ha! You just know you’re going to lose!”

They clash again, dick’s thrusting and parrying wildly. Their barbs are so sharp that it’ll only take one good stab to finish the fight. Sam’s ready af to just fill Dean up with so much jizz that he’ll be bulging with it, and he’ll give birth to a hoard of baby Sams.

There’s a noise from behind a nearby rock and they both turn to look. A third flatworm wriggles onto the top of the rock and waves its dick at them jovially. (Dicks only look jovial in very specific circumstances, and watching two hot flatworms dick-fight is one of them.)

“Don’t let me stop you!” the newcomer’s jovial dick-wave seems to say. “I was just waiting for you to finish so I could stab the winner while they were too exhausted to fight back.”

Sam finally recognises the newcomer. “Cas! What are you doing here?”

Dean’s eyeing his pointy barbs. “I didn’t even know you had a dick, Cas.” He sounds impressed.

There’s some complicated dick-waving subtext that never gets spoken out loud. Sam face-dicks, which is like face-palming except with a dick instead of a… you get the drift. He’s lucky he doesn’t take out an eye with his barbs.

“Please! Keep doing what you were doing,” says the Cas-worm via a lazy body-roll. He looks very relaxed as he leans against the rock.

“No one’s jizzing in Sam except me,” Dean aggressively wriggles back.

“Wonderful,” Cas agrees easily. Dean makes a frowny sort of face, which is pretty incredible given the lack of muscles or, even, face. “And then I will jizz in you.” If Dean had eyebrows and a forehead, the two would be meeting right now.

Sam and Dean share a look. Anyone else might think they were preparing for another round of dick-fencing, but they’re reaching a silent agreement. They nod and slap each other’s dicks like a non-worm might high-five or handshake, if they were so inclined.

They turn at the same time, and advance on Cas in tandem.

 

 

* * *

 

Sam has always admired Dean’s flatworminess, and he’s wanted to jizz in Dean’s abdomen for a long time. But as he advances on Cas with Dean by his side he finds himself even more enamoured (which is a complicated way of saying that the barbs of his dick want to bury themselves in Dean’s abdomen very very soon). There’s something about the way Dean worms. And yeah, it had made Sam horny when he was  _fighting_  Dean, but now they’re frill-to-frill (which is the flatworm version of shoulder-to-shoulder) and he’s somehow even hornier.

Luckily he knows exactly what to do with all the pent up horniness.

“First one to jizz in Cas is the winner!” he declares with a triumphant dick wave.

Cas creeps back a bit. “Now hang on,” he seems to be saying. He looks far less cocky than before. His dick is waggling about defensively.

“I’ll go round behind him,” Dean tells Sam.

“No,  _I’ll_  go round behind him. You distract him with a long meaningful gaze.”

“Do I get a say in this?” Cas asks. Nobody bothers replying.

“Frill dick scissors?” Dean suggests. Sam agrees that frill dick scissors is the perfect way to solve their argument. He picks frill. Dean picks dick. Neither of them pick scissors because nobody knows what the underwater equivalent of scissors is. This is a fatal flaw in the game and thus nobody wins. Especially not Cas.

As a compromise Sam worms his way around to one side and Dean worms his way around the other. Cas worms his way into a circle because he’s not great at the whole spatial awareness thing and he can’t figure out which way to go.

Dean gives a tremendous slap of his dick, and Sam takes the signal to go worming at top speed in Cas’s direction. Dean does the same on the other side. Cas doesn’t know which dick to defend himself from so he flattens himself to the seabed. Unfortunately he flattens himself with his dick poking upwards, and Sam accidentally trips over it in his rush. Sam flies into Dean, who tumbles into Cas, who doesn’t quite worm out of the way in time to avoid Sam falling into him.

When the sand clears, there are just three lonely flatworms left, and they all have a dick wedged into the flatworm next to them. The barbs stop anyone from pulling out while they all jizz into each other’s abdomen.

Dean flaps his frills in a courting display that’s about three seconds too late, considering Sam’s dick is literally inside him.

“We’re pregnant!” he undulates happily.

 

* * *

 

Sam looks suspiciously at the cocoon-shaped bulge in his abdomen. “Is it going to get much bigger?” he body-waves. (His dick has receded back into his abdomen so all communication is strictly via body waving, now.)

“I hope so,” Cas waves happily. He lovingly caresses his own cocoon-bulge. “Dean, don’t you hope so?”

Dean doesn’t reply. He’s off in the distance, circling another potential mate. Apparently one load of jizz wasn’t enough for him.

“Do you think they’ll like me?” Sam waves morosely. He’s making a puppy dog face because every version of Sam makes the same face.

“What self-respecting flatworm would like you?” Dean waves loudly (which is like yelling loudly except with really big frill-flaps). He’s covered in dick-sized holes and when he worms his way back to them he gives Sam a big, wet kiss. Big because flatworm kissing requires the whole body. Wet because Dean’s got white stuff all over his frills.

“Lucky for me you have no self-respect,” Sam waves drily, which is really an achievement because it’s hard to do anything drily in the ocean. Dean doesn’t reply because he’s too busy doing things off-camera to Cas.

But we all know he’s doing them.

_We know._

“Let’s go deposit our cocoons,” Cas muffles from underneath whatever Dean’s doing to him. Dean thinks that Cas shouldn’t be able to think about anything at the moment, so he does the thing with his frill tips again to shut him up.

Sam looks on in horror or appreciation, depending on your mood.

Eventually the cocoons actually really do get too big, and it’s time to deposit them. They find a nice weedy bit of growth and do some odd body-frilly-wavey-circley things.

“Why are we doing this?” Cas waves, dancing around a particularly stalky bit of seaweed.

“No one knows,” Sam replies.

“How are we supposed to deposit these cocoons?” Dean waves.

“No one knows that either.”

“We should give more funding to ecoscience,” Cas says, looking straight into the camera like Jim from The Office. Everyone nods.

The cocoons get deposited and Dean wipes a tear from his eye. “They grow up so fast.”

Sam notices that Dean is now cocoon-less. His dick extends a bit and he waggles it behind Dean’s back.

“No,” Cas warns. “The author doesn’t want to write any more of this shit. Put that back where it came from.”

Sam hesitates, but then Dean does a stupid sexy frill-wave and he sighs. He really can’t help himself. He stabs his dick directly into Dean’s abdomen.

 

 

**Author's Note:**

> Liked this fic? You might also enjoy [The McNugget AU](https://archiveofourown.org/works/10596669/chapters/23425575) by Unforth. Which is exactly what it sounds like.


End file.
